This is the Q&A for the Yard and Garden show for July 28, 2017. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and this will be the final episode from the show for 2017. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.
Guest Host: Kevin Christiansen and Evan Alderman, Agribusiness Instructors from Southeast Community College in Beatrice
If you enjoy reading my Q&A from the show each week, take my quick survey at: http://go.unl.edu/44qr and be entered to win a free plant book or some free UNL gifts. This Survey will Close on August 18th.
1.The first caller of the day wants to know if they can still treat for bagworms that were missed with the first application?
A. If the bag is less than 1 inch in length, insecticide applications will still be effective. However, if the bags are larger than 1 inch in length, the insecticides will not work very well. Because this tree has already been sprayed this year and still has bags, I would remind everyone to ensure that they spray efficiently and according to the label, leaving areas untreated can lead to more resistance if those bagworms contacted a small concentration of the chemicals that didn’t kill them.
2. This caller called to ask me what was the best insecticide to spray for bagworms, since I left that out on the first call?
A. Tempo or Bt would be most effective. Bt is the safer alternative because it won’t harm a lot of pollinators as it just targets insects in the Lepidopteran family of insects which includes butterflies, skippers, and moths.
3. A caller has a redbud tree that blew over in a storm this spring. The roots of this tree have begun to grow some suckers. Can one of those suckers be cared for to grow into another redbud tree?
A. Yes, the suckers can be trained into a new tree. It would help the growth of the one you choose to grow if you leave the other suckers for a while as well. All of the suckers will provide energy and food to the roots, so leaving extras for a while will help. Once the main stem gets growing, you can remove the others to push the one upright.
This caller also wanted to know if he can prune his magnolia tree so he can mow under it?
A. As long as the branches are not more than half the size of the trunk and as long as you aren’t removing more than a quarter of the overall canopy the branches may be removed. The best time to prune a magnolia tree is just after it blooms in the spring, pruning now will cut off flower buds that have already developed for next spring. If the branches that would need to be removed for mowing are too large, it might be wise to change the turf to shade perennials such as carex, bleeding hearts, hostas, coral bells, jack in the pulpit, jacobs ladder, Helleborus or Lenten Rose and many other great shade plants.
4. When is the correct time to prune a burning bush?
A. Late fall after the leaves fall off would be best. It is always easier to see the branches and where problem areas are if you prune in the dormant season. Also, it will allow the plant to quickly seal up the wounds in the spring flush of growth. It is not advised to prune now because pruning woody plants after the beginning of August until when they are dormant can hurt the plant. This may cause the plant to push new growth that would be more sensitive to cool temperatures causing more dieback in the plant.
5. A caller wants to know how do you know when Butternut and Acorn squash are mature?
A. These are both winter squash varieties so the fingernail test will work just as it does with a pumpkin. When you think the winter squash is mature, push your fingernail into the rind of the fruits. If your fingernail pokes through the rind, the squash is not mature, if your fingernail does not puncture the rind, it is a mature fruit. Winter squash should have a hard rind.
6. This caller wants to know how to control windmill grass in his lawn?
A. For perennial grassy weeds such as windmill grass, there are two options for managment, either use a Glyphosate product, such as roundup, on the weed and then reseed or use a product containing Mesotrione product, such as Tenacity, on the weed and not harm the grass. The tenacity is more expensive but will not kill your grass so there will be no need to overseed.
This caller also wanted to know what would be digging up his grass?
A. This is likely due to either skunks or racoons digging the grass trying to get to grubs living in the soil. See the following NebGuides to learn how to manage these animals: Raccoons and Skunks Also, if this is due to grubs, apply a grub control next June to reduce the grub population in your lawn.
7. A caller has tomato hornworms in her garden. How can they be controlled? She also wanted to know what grubs come from and how to control them?
A. Sevin will work to control hornworms. However, the population is not usually terrible and the hornworms can be removed by hand and thrown into a bucket of soapy water for control. Grubs are the immature form of Japanese beetles, May/June Beetles, Masked Chaffer for the majority of species in Nebraska. They can be controlled in June with a grub control like the Merit products that contain Imidacloprid.
8. This caller has a 1.5 foot tall tri-colored beech that was planted in full sun this spring. About a month ago, the leaves turned brown. The caller is watering it 2-3 gallons of water every other day. What is wrong with the Beech tree?
A. Beech trees like to be in a more protected location, so this tree may be getting too much sun and too much heat. Because it is such a small tree, there is still time to replant the tree in a more protected and slightly shadier environment. Also, this small of a tree would not need this much water. When replanting it, keep it watered every other day with only about 1 gallon of water each time. After a few weeks in it’s permanent location, you can water with 1-2 gallons of water once a week and continue to back off on days between each watering as the tree grows larger. Remember, this small of a tree will not have a very large root system and it is as easy to overwater a tree as it is to underwater one.
9. How do you control moles in the lawn?
A. Moles are best controlled with a Harpoon trap that can be purchased at most hardware stores. For management tips, see this NebGuide on Moles
10. This caller has a hibiscus tree with a braided trunk that she thought would grow to zone 4, is this hibiscus going to be able to survive in Nebraska winters?
A. Unfortunately, it is highly unlikely that this is a hardy hibiscus that will survive winters in Nebraska. There is a hardy hibiscus that will survive our winters outdoors and those are suited up to zone 4, there is also a tropical hibiscus that is sold here as an indoor plant and will not survive our winter conditions outdoors. I would say that the tropical hibiscus would be the type purchased with a braided trunk. It can survive indoors during the winter months, so she can dig it up and put it into a pot to bring indoors for the winter.
This caller also wanted to know how to control clover?
A. Clover should be managed in the fall of the year. It will take multiple applications over multiple years to fully control clover in the lawn. Use 2,4-D or triclopyr products in the fall. It is best to apply these products around September 30th and again around the middle to the end of October.
The final question from this caller was if she should cut back her Virginia creeper plant that is turning brown?
A. Leave it alone and allow the plant to come out of the browning on its own. This is a common problem with Virginia creeper that is not terribly damaging to the plant.
11. How do you control anthracnose in tomato plants?
A. A copper fungicide can be used in a vegetable garden if necessary. However, often with home vegetable gardens it isn’t worth the time and money to spray our vegetable crops as the diseases usually only last for a short time and then fade when the temperatures change a little. However, it seems for this caller that the disease is a problem every year. For more information on controlling the disease and how to manage your vegetable gardens to avoid disease problems, visit this Nebguide on Leaf and Fruit Diseases of Tomatoes.
12. A caller has carpenter bees digging holes in her shed and wants to know how to control them?
A. Carpenter bees are a beneficial insect, except when they are burrowing into the wood framing of buildings reducing their structural integrity. They are best controlled with a dust formulation of sevin. Leave the dust in the holes a few days and then the holes can be filled in with a wood putty. For more information, see this guide from Lancaster County Extension on Carpenter Bees.
13. The final caller of the day wants to know how to control ragweed?
A. At this point, the plant is growing too strong to be killed with a herbicide. The best time to treat is in the spring before the plants have grown too large. At that time, they can be treated with 2,4-D. Now, the best control would be to dig or chop out the plants.